TRANSACTIONS OF THE SECTIONS. 119 
systems as far removed from its direct influence as the osseous and dental; and 
all these particularities, together with those of the systems with which they were 
correlated, were much more marked in the Whales than in the Seals. 
The Seals were well provided with intrahepatic venous sinuses, but their reser- 
voirs for arterial blood were far inferior in grade of development to those of the 
Cetacea. Little could be said as to difference in the degree of patency in the fora-. 
men ovale and ductus venosus in the two subjects of comparison, at least so far as 
the Common Seal (Phoca vitulina) and Common Porpess (Phocena communis) 
might serve as representatives of the two orders. To the rudiments of the foetal 
vena umbilicalis and ductus Botalli, in both, the same remark applied. 
The stunted salivary glands of the Seals seemed an approximation to the con- 
dition of total absence which we find in carnivorous Cetacea; and, but that some 
of the latter class possessed olfactory bulbs, a similar relation might be said to 
prevail between these organs also in the two orders. 
In both classes alike, the weight of the brain was high as compared with that 
of the body: ina young Phoca vitulina Dr. Rolleston had found it to be as 1: 46; 
in a young Phocena communis, as 1: 60. 
The bark of the Seal spoke plainly enough to its want of any such arrangement 
of the larynx as the Whales possess; but a recent inspection of a large Seal (Pela- 
gius monachus) had shown it to possess an exceedingly strong sphincter muscle 
guarding the entrance to the respiratory passages, and it might be conjectured that 
the membrano-muscular pouch in connexion with the nasal passages in the Stem- 
matopus cristatus was a foreshadowing of the sac so often described in connexion 
with the Cetacean blow-hole. 
Several foetal structures were permanently retained in the Cetacea, The thymus, 
as shown by Mr, Turner (Edin. Phil. Trans. xxii. pt. 2), was one of these ; certain 
other remnants of the general formative mass of blastema which surrounds 
the aorta in the foetus, noticed by himself in the ‘Natural History Review’ for 
Oct. 1861, furnished a second example; and to these the author would now add a 
third, in the largest remnant of a Wolffian body, or organ of Giraldés, which he 
had met with in the class Mammalia. The author proceeded to say that, in the 
two classes of birds which he had to contrast, scarcely any such approximations 
could be traced between the two sets of structures to be compared. 
The modifications in the tibie' of the birds commonly known as “ divers” 
(Colymbine), and the large intrahepatic venous sinuses which they, in common with 
the mammals just spoken of, possessed, were beautiful adaptations to the special 
habits of these animals ; but nothing at all reminding us of these structures would be 
found in such a bird as the Water-Ouzel (Cinclus aquaticus). Indeed, the soft 
parts of this bird presented yery few points of difference from those of a Redwing 
(Turdus ilacus) dissected at the same time with it, except in the much greater 
development of the second pectoral muscle. The large size of this muscle was per- 
manently recorded on the keel of the Ouzel’s sternum; and this point might 
perhaps have enabled us, @ priori, to predict that the bird possessed the peculiar 
habits which have given it its trivial name. This ridge extends the whole length 
of the keel in the Water-Ouzel ; and in this point, as well as in the lesser relative 
depth of that process, and in the greater relative breadth of the lateral portions of 
the sternum, and in its more nearly circumscribed posterior emarginations, the bird 
in question differed from allied species of dissimilar habits. 
Recent Experiments on Heterogenesis, or Spontaneous Generation, 
By James SaAMvELson. 
The author communicated the results derived from the simultaneous exposure of 
various kinds of infusions prepared. by him in Hull, Paris, and Liverpool. Amongst 
these results the following afford fresh evidence against the theory of spontaneous 
generation, and tend to prove the existence of innumerable germs of life in the at- 
mosphere. 
Dr. Balbiani (the author’s coadjutor in Paris) found certain well-defined species 
of Infusoria in his infusions, which he also discovered in the moistened dust from 
his window ; and another well-marked species, found in large numbers by Dr. Bal- 
